The present invention pertains to a pressure fluid actuated in-the-hole reciprocating piston hammer percussion rock drill including a sleeve type pressure fluid distributing valve, fixed or bit actuated guide shoes, an improved directional or steerable drill bit and a method for steering a drill including a steerable drill bit.
In the art of pressure fluid actuated reciprocating piston percussion rock drills and similar percussion tools, it is known to provide the general configuration of the tool to include a sliding sleeve type valve for distributing pressure fluid to effect reciprocation of a fluid actuated piston hammer. There are many applications of these types of drills wherein the diameter of the hole to be drilled is relatively small, in the range of two to three inches, for example. Still further, there are also applications for reciprocating piston percussion rock drills and similar tools wherein the tool must be inserted within a conduit or tubing string for cleanout of the conduit or for utilization of the conduit as a guide structure.
One improvement in small diameter reciprocating piston percussion rock drills and the like is disclosed and claimed in my U.S. Pat. No. 5,680,904, issued Oct. 28, 1997. The percussion rock drill disclosed in the ""904 patent includes opposed sleeve type valves disposed on opposite reduced diameter end portions of the reciprocating piston hammer, respectively, for movement with the piston hammer and for movement relative to the piston hammer to distribute pressure fluid to opposite sides of the piston hammer to effect reciprocation of same. Another advantageous design of a relatively small diameter fluid actuated percussion rock drill is disclosed and claimed in U.S. Pat. No. 4,828,048 to James R. Mayer and William N. Patterson. The drill described and claimed in the ""048 patent utilizes a single sleeve type distributing valve disposed at the fluid inlet end of the drill cylinder. However, the construction of a drill in accordance with the ""048 patent tends to restrict the minimum outside diameter or require that the fluid passages and/or the piston diameter be of inadequate size for certain applications.
Accordingly, since it is desirable to provide maximum drilling energy in most applications of percussion rock drills within the constraints of the requirements of the outer diameter of the drill, and it is also considered desirable to be able to xe2x80x9csteerxe2x80x9d the drill in certain applications thereof, there have continued to be needs for improvements in the construction of relatively small diameter hydraulic or other pressure fluid actuated percussion rock drills. It is in pursuit of these objectives that the present invention has been developed.
The present invention provides an improved pressure fluid actuated reciprocating piston percussion tool, particularly adapted for rock drilling. The invention contemplates, in particular, the provision of a relatively small diameter, hydraulically actuated, reciprocating piston type percussion rock drill which is characterized by a single sleeve type pressure fluid distributing valve which is mounted within the drill cylinder between the enlarged diameter piston portion of the reciprocating piston hammer and the forward, percussion bit end of the tool or drill.
In accordance with another aspect of the present invention, a hydraulically actuated reciprocating piston percussion rock drill is provided which includes a reciprocating sleeve type fluid distributing valve which is pressure fluid actuated to move in opposite directions in sleeved relationship around a reduced diameter hammer portion of the reciprocating piston hammer. The piston hammer is continually biased by pressure fluid in one direction and the sleeve valve operates to alternately pressurize and vent a pressure fluid chamber acting on the opposite side of the piston portion of the piston hammer to effect reciprocating impact blow delivering movement thereof.
In preferred embodiments of the invention, a reciprocating piston percussion rock drill is provided with a unique tubular sleeve type pressure fluid distributing valve which is pressure fluid actuated to move in opposite directions and is cushioned by pressure fluid to arrest movement of the valve and to effect acceleration of the valve in the opposite direction. In one preferred embodiment, the distributing valve is momentarily exposed to a vent passage in the piston hammer which vents pressure fluid via passages in the drill cylinder to the exterior of the drill to facilitate valve movement. In another preferred embodiment, the distributing valve is momentarily exposed to a vent passage which vents through the piston hammer and a passage in the drill bit.
In accordance with another aspect of the invention, a reciprocating piston pressure fluid actuated rock drill is provided with an improved construction and arrangement of a pressure fluid distributing valve and a reciprocating piston hammer which cooperate to provide for conducting pressure fluid through the piston hammer to the drill bit for hole flushing purposes without reciprocating the piston hammer.
In accordance with yet a further aspect of the present invention, a relatively small diameter pressure fluid actuated reciprocating piston percussion rock drill is provided which includes substantially unobstructed pressure fluid flow passages which improve the efficiency of the drill and result in converting more energy stored in the pressure fluid to percussion blows acting on the drill bit.
In accordance with still another aspect of the present invention, a reciprocating piston percussion type rock drill is provided with an improved arrangement of fixed and moveable stabilizer or guide shoe members mounted on the drill cylinder adjacent the bit end thereof.
The present invention further provides a reciprocating piston percussion rock drill with an improved steerable or so-called directional drill bit for use therewith for directional drilling purposes. In one embodiment of the steerable or directional bit and drill combination, a chuck is provided for attachment to the drill cylinder body which includes spiral internal splines and a bit is provided with cooperating spiral external splines which provide for limited rotation of the bit with respect to the chuck and cylinder to provide for directional drilling. Use of the spiral splined bit and chuck combination with the pressure fluid actuated drill of the present invention also provides an improved method of directional drilling.
Still further, the present invention provides a hydraulic pressure fluid actuated reciprocating piston percussion rock drill or similar tool which includes an overall improved construction, provides for ease of assembly, disassembly and replacement of working parts, if necessary, is efficient in operation and is particularly adapted for drilling relatively small diameter holes.
Those skilled in the art will further appreciate the above-mentioned features and advantages of the invention together with other superior aspects thereof upon reading the detailed description which follows in conjunction with the drawing.